Ohm.
The "ha" Sutra and the shakti of a billion mantras!
The expression "agaram to kshakaram" refers to the 51 letters between "a" and "ksha." Within these are the letters and sounds of all languages.This is also the root of the western expressions "from A to Z" and "from alpha to omega."

Words such as Akshaya, Akshaya-Vatam and Akshaya Tritiyai juxstapose these first and last syllables and
signify complete well being. This is the Siddha secret behind the wonderful "
depression curing mantra" given by Sathguru Venkataraman that we mentioned earlier.

For each of these 51 letters from "a" to "ksha," there are one crore (10,000,000) mantras that Siddhas and rishis have received and given to us. Thus a total of 51 crore (510 million) mantras! And all of these have the shakti of the "ha" Maheswara Sutra beejakshara!

Apart from the 51 crore mantra classification mentioned above, other classifications of 72 crore mantras and 108 crore mantras also exist.
We published this and the previous posts on the 2015 Karthigai Deepam some days ago in this blog, at the beginning of the 2015 Karthigai Deepam Festival. But since those posts were deleted by mistake, we are reposting them again. The article in the website has all of this info of course.

Ohm Arunachala Shiva, Arunachala Shiva, Arunachala Shiva, Aruna-ShivOhm.